Process for building pneumatic tires



Nov. 26, 1957 M. vANzo ETAL 2,814,331

PRocEss Foa BUILDING PNEUMATIC TIRES Filed April 2o, 195e z sheets-shewL1 l2 Imm le Y 1 lo i Y K DARIO -GILETTA a sa ULISSE NUARA ATTORNE S Nov.26, 1957 Y M. vANzoI ETAL 2,814,331

PRocEss FOR BUILDING PNEUMATIpTIREs Filed April 20, 1956 2 Sheets-Sheet2 III /1".... V/////////;.'.L\\\\\\\Yei/////ll/ 25 n l ...-mmw

- JNVENToRs 6a MARCELLO VANZO,

DARIO GILETTA a FIGB ULISSE NUARA 2,814,331 Patented Nov. 26, 1957 dicePRCESS FR BUILDING PNEUMATIC TIRES Marcello Vanzo, Dario Giletta, andUlisse Nuara, Milan, Italy Application April 20, 1956, Serial No.579,507

20 Claims. (Cl. 154-14) The present invention relates to a new andimproved method for the manufacture of pneumatic tires which may havegeneral utility in this field and may be used for the manufacture ofstandard types of pneumatic tires. However, the method is particularlyadapted and designed for the purpose of meeting certain problemsconnected with the practical manufacture of tires constructed as shownand described in the copending application of Luigi Emanueli, Serial No.274,085, filed February 29, 1952, now abandoned, to which applicationreference may be made.

In order to make clear the method of the present invention, thedistinctive features of the tire shown in the said Ernanueli applicationshould be understood. The tire of the said application is characterizedby a carcass or body composed of rubberized plies of radially arrangedcords and by a substantially inextensible breaker located between thecarcass and the tread, the breaker being composed of at least one bandhaving at least two superposed plies of parallel cords which aresubstantially inextensible. For this purpose, the breaker strip or beltis constructed of parallel strands, either textile or wire cords orcables, of very low elongation and arranged at oppositely disposedangles having values from 5 to 20 to a plane perpendicular to therotational axis of the tire.

This breaker structure is held under tension and because of itsconstruction and because it operates as a stricture band, the treadportion of the tire has a substantially flat, ground-contacting area.Due to the new construction described, the tread portion of the tire ismaintained in a substantially flat condition, and the contraction andexpansion of the area of the tread in contact with the ground is greatlyminimized. These features of the tire result in substantially reducedtread wear, less consumption of fuel and other advantages more fully setforth in the aforesaid application.

lt will be understood, however, that the breaker belt or stricture bandis not completely inextensible when built into the tire, for a limitedextensibility is desirable due to the necessity of allowing for alimited expansion of the tire in the mold or press during the curingoperation that will remove any waviness in the cords of the carcass andgive a satisfactory molding operation.

The accepted and standard method of building tires is the so-called datband or drum building method in which the plies of rubberized cordfabric constituting the carcass are laid over a ilat, drum-likestructure, the edges of the plies being wrapped in various methods aboutthe beads, which are located in bead seats on the edges of the drum. Thetread is now applied to the central portion of the carcass and, as isthe common practice, the usual breaker strips or strip, which liebetween the tread and the carcass, are applied at the same time.Sidewalls, chafer strips and other parts of the tire are then added. Thedrum is collapsed and the tire in flat band or pulley band form isremoved and shaped and cured. This operation is done by bringing theband into substantially tire form and then inserting a `curing bag onwhich the tire is cured in a mold while held underinternal pressure orthe band is placed in a press in which it is shaped and cured underinternal pressure contained in a diaphragm located in the press.

This dat building method is universally adopted and used because it iseconomical, the building of a tire requires no particular skill oraptitude, and the standard tires perform well although they do not havethe special attributes of a tire made in accordance with the aforesaidapplication.

In the building of the tires of the aforesaid application, it isdesirable to utilize many of the beneficial and standardized features ofthe flat band method, but due to the special construction and propertiesof the breaker belt, which inhibit any substantial expansion of thecentral part of the carcass, it is impossible to employ existingmachines and existing methods.

ln order to build a tire of the construction of the said Emanueliapplication and to manufacture such a tire so that it will meet theexacting standards which are required in order best to realize thebeneficial results of the Emanueli invention, the applicants havedevised the method shown and described herein. This new and usefulmethod has been devised to utilize to such an extent as may be possiblethe almost universally used process of the dat band or pulley bandmethod, but it has been necessary to create certain new procedures to beused in combination with the technique of the standard tire buildingmethods in order to achieve the aims of the present invention. y

The present application is a continuation-impart of applicants priorapplication Serial No. 391,364, filed November 10, 1953, the saidapplication being directed to a new and useful machine for building thetires of the Emanueli invention.

In the description and the accompanying drawings there are shown thesteps of the process of this application; also details of a simpleapparatus for carrying out the process.

It will be understood, however, that the description and drawings arefor the purpose of making the invention clear to those skilled in thisart and that the invention is not necessarily restricted thereto but issubject to modification and improvement without departure from the basicprinciples thereof.

In the drawings, in which is shown a portion of the building drum whichis used in carrying out the process:

Fig. 1 is a view showing the rst or band ply or plies laid over thedrum.

Fig. 2 shows the application of the beads.

Fig. 3 shows the application of the over bead ply or plies.

Fig. 4 shows the shaping rings moved into position.

Fig. 5 shows the preliminary shaping of the carcass and the applicationof the breaker strip or stricture belt.

Fig. 6 shows the application of the tread.

Fig. 7 shows the condition of the uncured tire when the shaping ringsare removed.

Fig. 8 shows the stitching of the tread and sidewalls on the carcass.

Fig. 9 shows a detail of the finishing operation.

Fig. 10 is a view showing the arrangement of the breaker belt and thecords of the carcass which is characteristic of a tire made inaccordance with the invention of the aforesaid Emanueli application.

Referring first to Fig. 10, the tire of the Emanueli invention consistsof a carcass of rubberized cord fabric, the cords of which are laidradially or approximately radially of the tire, that is to say, parallelto or approximately parallel to the axis of the tire. Such anarrangement of the cords is shown at A in Fig. 10. The breaker unitpreferably consists of at least two rubberized layers or plies ofparallel cords or strands which may be either textile cords or wirecables. These two plies are indicated at B and B. The cords or strandsare laid at a very long angle or, stated in another way, in an angularposition which very closely approaches a plane transverse to the axis ofrotation of the tire. The cords, in two layers, are arranged at oppositeangles and are preferably laid at angles having values ranging from to20 to a platte transverse to the axis of rotation of the tire. Thestrands which comprise the breaker element have a very limited degree ofelongation, as described above, with the result that the tread of thetire is held in sub stantially iiat condition to accomplish the usefulresults of the Emanueli invention. The breaker band or belt is oftenreferred to as a stricture belt because of its properties of holding thetread area of the tire substantially flat across the tire. As notedabove, this stricture belt inhibits the building of the tire by standardmethods in which the breaker strips and tread are laid over the carcasswhile it is on the fiat building surface and the subsequent shaping ofthe uncured tire is possible because of the extensibility of the centralportion of the structure. However, such expansion is not possible in thebuilding of a tire of the Emanueli construction.

The tire is built on a flat, rotatable building form which is composedof a at cylinder made of a sheet 3 of rubber or other similar extensiblematerial. The edges of the sheet are formed with enlarged beads or ribs4 and 4a and each edge is clamped between a flat disc 5 or 5a and aplate 6 or 6a, so that the sheet and the end members constitute a hollowenclosed chamber 8 which is airtight. The chamber is connected to aconduit through which air under pressure can be introduced into thechamber or evacuated therefrom.

The discs 5 and 5a are mounted so that they are moved outwardly to holdthe sheet 3 taut, but air at a slight degree of superatmosphericpressure may be maintained in the chamber so that the sheet 3 will makea firm building surface. To shape the tire carcass, as will be morefully set forth later, the pressure of the air in the chamber 3 isincreased and the sheet 3 is expanded outwardly to shape the carcass atthe same time that the discs are moved inwardly, as shown in Figs. 5 to8, inclusive. lt is desirable to advance the discs 5 and 5a at a rateproportionate to the increasing expansion of the sheet 3.

To remove the finished tire, the chamber may be evacuated so that thesheet 3 is drawn inwardly and at the same time the discs are movedinwardly slightly, as shown in dotted lines in Fig. 8, so that the tiremay be removed by ovalizing one beaded edge thereof and passing it intothe space between the discs and then by ovalizing again said beaded edgeso that it can be slipped off the building form.

The first or under bead ply or plies are given the reference numeral l0.This part of the carcass is laid over the drum provided with the beadseats 11 and 11a formed on the outer periphery of the discs 5 and 5a.

The next step is the application of the beads 12 and 12a to the edges ofthe first ply where they are located on the bead seats. A mechanism toapply the beads is shown in Fig. 2 and consists of hat rings 14 and 14awhich are carried on the inner side of two hoods or frames 15 and 15amovable toward and away from the drum, as more fully set forth in theaforesaid application Serial No. 391,3 611. Pins 16 and 16a on which therings 14 and 14a are mounted shift the beads from the rings and pressthem onto their respective bead seats when the hoods are moved inwardlytoward the drum. The hoods are now withdrawn.

The next step is the application of the over bead ply or plies 18 to thesurface of the drum and over the beads so that the edges of those pliesoverhang the sides of the drum. The plies may be rolled in place toinsure adhesion of the plies as is usual.

The carcass is now ready to receive the breaker and tread. he breakerelement is given the numeral 20.

5 the breaker element.

It may consist of two or more plies or layers of strands, the propertiesof which have been described. If the breaker is of substantialthickness, fillets of rubber 21 may be added to the edges of the breakerelement to avoid an abrupt step-off at the edge of the breaker. Thetread is of the usual design and is given the numeral 24. It may beapplied as a separate element, as shown in Figs. 5 and 6, or the breakerand tread may be preassembled before applying them to the carcass.

As the breaker element is substantially inextensible and is ofsubstantially greater inner circumference than the outer circumferenceof the unshaped carcass, the carcass is expanded so that at its crown itis the same, or substantially the same, outer diameter as the innerdiameter of It is essential that the carcass be expanded to the exactdimension to receive the breaker before it is applied.

For reasons stated, when the building drum is expanded, two shapingrings of greater diameter than the carcass are moved into position overthe form. These rings are indicated by the numerals 25 and 25a and areconveniently carried on the hoods 15 and 15a. Either before or as thecarcass is being shaped by the expansion of the sheet 3 and the approachof the discs S and 5a, these rings are moved into position as shown inFig. 6, but with the opposing edges spaced apart so as to leave thecrown area of the carcass exposed. The inner edge of rings 25 and 25aare concaved slightly, as shown at 26, so as to conform to the curvatureof the expanded carcass.

The rings 25 and 25a not only serve to limit the expansion of thecarcass to the exact degree which was predetermined, but they also serveas a base over which the breaker and tread are applied to the carcass atthe exact dimension required. To accurately center the breaker, guides28 may be provided on the rings 25 and 25a.

The breaker is applied to the surface formed by the rings 25 and 25a,which rotate with the drum, and the exposed central area of the carcass.

The breaker 26 is now rolled into adhesion with the central zone of thecarcass and the tread 24 is wrapped about the rings 25. These elementsmay be rolled in place by the workmen who may use automatic stitchingrollers 3!) for the purpose, the construction and operation of which areset forth in the aforesaid application Serial No. 391,364.

The rings 25 and 25a are now withdrawn to the dotted line positions andthe discs 5 and 5a moved together, as shown in Fig. 7, leaving the tirein the condition shown. At this time it is desirable to increase thepressure to approximately operative running pressure or about 1.5atmosphere. Due to the presence of the stricture belt, the tire willassume the shape, or approximately the hape, shown in Fig. 7 with thetread area transversely The tread and breaker element are now stitchedin place manually or by the rollers 30 which are advanced around thetire as shown by dotted lines in Fig. 8 by mechanism such as shown, forexample, in the aforesaid application Serial No. 391,364. At the sametime the side walls 32 may be stitched onto the tire and those elementsmay be preassembled with the tread or applied separately.

The tire is now removed from the building form in the manner heretoforedescribed. The edges of the over bead plies may now be trimmed oif orwrapped about the beads as shown in Fig. 9 to complete the tie-in of thebeads.

The addition of chafer strips or 1other finishing operations may now beperformed and the tire is shaped and vulcanized on air bags in molds orin presses equipped with means to expand the tire to its final form inthe curing molds.

It will be seen that a novel and ingenious method has been devised forthe efficient building of a tire of the special design or of anystandard design. The important breaker element is correctly applied andof exact dimensions to secure the maximum value of the Emanueliinvention.

What is claimed is:

1. The method of building a penumatic tire comprising laying plies oftire builiding fabric about a drum the body of which is expansible,turning the edges of the fabric inwardly at the sides of the drum toform bead seats which are of lesser diameter than the outer diameter ofthe sides of the drum, locating beads in said bead seats, applyingadditional plies of fabric over the first said plies and over the beads,thereafter expanding the body of the drum to bring the central portionof the carcass to approximately its final circumference while moving thebeads together, attaching a substantially inextensible breaker to thecrown of the expanded carcass, applying a tread to the breaker, rollingthe breaker and the tread onto the carcass, and then removing the tirefrom the drum and vulcanizing it.

2. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the body of which is expansible,turning edges of plies inwardly at the sides of the drum incorporatingbeads of lesser diameter than the outer diameter of the sides of thedrum in the inwardly turned edges of the fabric to complete the carcass,expanding the body of the drum to bring the central portion of thecarcass to approximately its nal circumference while moving the beadstogether; attaching a substantially inextensible breaker to the crown ofthe expanded carcass and applying a tread to the breaker after havingcentered said tread and said breaker by guide means, rolling the breakerand the tread onto the carcass, and then removing the tire from the drumand vulcanizing it.

3. A method in accordance with claim 1 in which the beads are propelledtogether at a rate proportionate to the increasing expansion of the bodyof the drum.

4. A method in accordance with claim l in which the tire is removed fromthe drum by collapsing the expansible central portion of the drum andmoving further together both sides of said drum, ovalizing a bead of thetire, passing the said bead into the space between the sides of the drumand then over the other side of the drum.

5. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion which isexpansible, incorporating beads in the edges of the plies to completethe carcass, bringing expansion limiting members over but spaced fromthe periphery of the drum, expanding the central portion of the carcassto approximately its final circumference within said members, attachinga breaker to the crown of the expanded carcass, applying a tread,rolling the breaker and the tread onto the carcass, and then removingthe tire from the drum and vulcanizing the tire.

6. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion of which isexpansible, incorporating beads in the edges of the plies to completethe carcass, bringing expansion limiting members over but spaced fromthe periphery of the drum, expanding the central portion of the carcassto approximately its linal circumference within said members, whilebringing the beads together, attaching a breaker to the crown of theexpanded carcass, applying a tread, rolling the breaker and the treadonto rthe carcass, and then removing the tire from the drum andvulcanizing the tire.

7. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion of which isexpansible, incorporating beads in the edges of the plies to completethe carcass, bringing expansion limiting members over but spaced fromthe periphery of the drum, expanding the central portion of the carcassto approximately its final circumference within said members whilebringing the beads together, attaching a breaker to the crown of theexpanded carcass and applying a tread after having centered said treadand said breaker by guide means, rolling the breaker and the tread ont-othe carcass, and then removing the tire from the drum and vulcanizingthe tire.

8. A method in accordance with claim 6 in which the beads are movedtogether at a rate proportionate to the increasing expansion of the bodyof the drum.

9. A method in accordance with claim 5 in which the tire is removed fromthe drum by collapsing the expansible central portion of the drum andmoving further together both sides of said drum, ovalizing a bead of thetire, passing the said bead over one side of the drum into the spacebetween the sides of the drum and then over the other side of the drum.

10. A method in accordance with claim 5 in which the breaker is asubstantially inextensible belt.

11. A method in accordance with claim 6 in which the breaker is asubstantially inextensible belt.

l2. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion of which isexpansible, turning edges of the plies inwardly, incorporating beads inthe inturned edges of the plies to complete the carcass, locatingexpansion limiting rings over but spaced from the periphery of the drumand spaced from one another, expanding the central portion of thecarcass until further expansion of the carcass is restricted by therings, attaching a breaker to the exposed area of the carcass betweenthe rings, applying a tread, rolling the breaker and -the tread onto thecarcass, and then removing the tire from the drum and vulcanizing thetire.

13. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion of which isexpansible, incorporating beads in the edges of the plies to completethe carcass, locating expansion limiting rings over but spaced from theperiphery of the drum and spaced from one another, expanding the centralportion of the carcass while bringing the beads together until furtherexpansion of the carcass is restricted by the rings, attaching a breakerto the exposed area of the carcass between the rings, applying a tread,rolling the breaker and the tread onto the carcass, and then removingthe tire from the drum and vulcanizing the tire.

14. The method of building a pneumatic tire comprising laying plies oftire building fabric about a drum the central portion of which isexpansible, incorporating beads in the edges of the plies to completethe carcass, locating expansion limiting rings over but spaced from theperiphery of the drum and spaced from one another, expanding the centralportion of the carcass while bringing the beads together until furtherexpansion of the carcass is restricted by the rings, attaching a breakerto the exposed area of the carcass between the rings, and applying atread after having centered said tread and said breaker by guide means,rolling the breaker and the tread onto the carcass, and then removingthe tire from the drum and vulcanizing it.

l5. A method in accordance with claim 1-3 in which the beads arepropelled together at a rate proportionate to the increasing expansionof the body of the drum.

16. A method in accordance with claim l2 in which the tire is removedfrom the drum by collapsing the expansible central portion of the drumand moving further together both sides of said drum, ovalizing a bead ofthe tire, passing the said bead over one side of the drum into the spacebetween the sides of the drum and then over the other side of the drum.

17. A method according to claim 12 in which the breaker is asubstantially inextensible belt.

18. A method according to claim 13 in which the breaker is asubstantially inextensible belt.

19. The method of building a pneumatic tire comprising laying plies oftire building material about a drum the body of which is expansible,incorporating beads in the edges of the material and completing thecarcass, expanding the body of the drum to bring the central portion ofthe carcass to approximately its nal circumference while propelling thebeads toward each other at a rate proportionate to the increasingexpansion of the body of the drum, applying tread elements to theexpanded carcass, removing the tire from the drum, and vulcanizing thetire.

20. The method of building a pneumatic tire comprising laying plies oftire building material about a drum the body of which is expansible,incorporating beads in the edges of the material and completing thecarcass, inflating the body of the drum to bring the central portion ofthe carcass to approximately its final circumference while propellingthe beads toward each other at a rat-e proportionate to the increasingexpansion of the 8 body of the drum, applying tread elements to theinated carcass, evacuating the drum, ovalizing one bead of the tire,passing the said bead into the space between the sides of the drum andthen over the other side of the drum to remove the tirc from the drum,and vulcanizing the tire.

References Cited in the le of this patent UNITED STATES PATENTS2,084,009 Sohl June 15, 1937 2,182,176 Maranville Dec. 5, 1939 2,565,071Frazier Aug. 21, 1951 2,567,064 Frazier Sept. 4, 1951 2,614,951 IredellOct. 21, 1952 2,715,932 Frazier Aug. 23, 1955

